The studies outlined in this proposal have as a major objective the continuation and expansion of an ongoing research program in our laboratory, and we would like to advance our current results towards an investigation of a few specific areas related to the transplantation of pancreatic islets. Firstly, concanavalin A has been used as a probe to investigate beta cell membrane characteristics: A major effort will now be made toward the characterization of the structure and chemical composition of islet membranes and to correlate these findings with functional characteristics and transplantability of islets. Secondly, other aspects of islet transplantation were investigated such as the effect of donor age on the transplantability of islets, the effects of transportal injection of islets on liver metabolism and the transplantation of culture-maintained islets into rats with diabetes of long-term duration. We now wish to apply the basic techniques developed for these studies towards the transplantation of the of the severely diabetic animal. Thirdly, we have studied the effects of islet transplantation on renal function and glomerular lesions in the diabetic rat. We plan to expand these studies to determine the alterations in glomerular permselectivity seen in diabetic rats and the effect of transplantation on permselectivity.